Intermolecular condensation of hfinsoluble linear fused-ring polycyclic aromatic hydrocarbons



A. P. LIEN 2,525,809 INTERMOLECULAR CONDENSATION 0F HF-INSOLUBLE LINEAR Oct. 17, 1950 FUSED-RING POLYCYCLIC AROMATIC HYDROCARBONS 2 Sheets-Sheet 1 Filed July: 10, 1947 1950 A. P. LIIEN INTERMOLECULAR CONDENSATION 0F HF Oct. 17,

2,525,809 INSOLUBLE LINEAR v 'FUSED-RING POLYCYCLIC AROMATIC HYDROCARBONS Filed July 10, .1947

2 Sheets-Sheet 2 MCO kG 0 039*:

fiatented oct. l7, l9 0 UNITED STATES PATENT OFFICE INTERM-OLECULAB' ooNnENsA'rIoN or F= INSOLUBLE' LINEAR FUSED-RING POLY: CYCLIG' AROMAT-IC HYDROCARBONS Arthur F. Lien, Hammond, Ind., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana Application July 10, 1947, Serial No. 760,061-

2 Claims.

. 1 This invention relates to a process for efiecting the intermolecular chemical condensation of certain polycyclic aromatic hydrocarbons. More particularly it relates. to a process for the separation of substantially HF-insoluble polycyclic aromatic hydrocarbons such as naphthalene and alkyl naphthalenes from their mixtures with saturated hydrocarbons by a process which involves intermolecular chemical condensation of said aromatic hydrocarbons to produce I-IF-soluble polynuclear aromatic hydrocarbons which are extracted. from said saturated hydrocarbons, both the chemical condensation-and extraction steps: being performed in a medium consisting essentially of liquid anhydrous hydrogen fluoride which functions as a catalyst in the chemical reaction and a solvent in the extraction operation.

This application is a continuation-in-part of my previous application for Letters Patent S. N.

681,122 filed on July 2, 1946, now U. S. Patent No. 2,426,624, patented September 2, 1947.

Although the literature has indicated that liquid hydrogen fluoride is a solvent in general for aromatic hydrocarbons, I have found that this is not true, strictly'speaking. Thus, I have observed that monocyclic aromatic hydrocarbons are substantially insoluble in liquid hydrogen fluoride. Moreover, I have found, as more fully set forth in U. S. Patent No. 2,426,624, that polynuclear aromatic hydrocarbons of quinonoid structure exhibit substantial solubility'in liquid hydrogen fluoride whereas under-similar conditions polynuclear aromatic hydrocarbons of benzenoid structure are substantially insoluble in liquid hydrogen fluoride. Examples of benzenoid type polynuclear aromatic hydrocarbons are naphthalene, alkyl naphthalenes and phenanthrene. Examples of quinonoid type polynuclear aromatic hydrocarbons are anthracene, pyrene and perylene. v

There are numerous instances in which it is desirable toseparate saturated hydrocarbons, viz. alkanes, cycloalkanes and alkylcycloalkanes, from associated polycyclic aromatic hydrocarbons of similar boiling range. Thus, it is desirable to remove aromatic hydrocarbons including HF- insoluble polycyclic aromatic hydrocarbons from kerosenes or heater oils to depress their soot-v producing capacity upon combustion. It is "desirable to remove aromatics from gas oils, either virgin orcracked, toimprove their cracking-characteristies. It isalso desirable to remove aromatics from Diesel fuel fractions to improve cetane number. The removal of certain aromatics A from lubricating oil fractions increases V. I. and

reduces carbonization tendencies. Another application of this invention is in the separation of alkylnaphthalenes, particularly methylnaphthalenes; from hydrofor mer bottoms. 7 of the presentinvention afiords not only a method of separatingcertain aromatic hydrocarbons from saturated hydrocarbons but also leads to the pro-. duction of-valuable HF-soluble polynuclear aromatic hydrocarbons. The process of this. invention may also be applied to effect the chemical condensation of naphthalene and alkylnaphtha lanes in fractions derived from coal tar or by coal hydrogenation.

One object of my invention is to provide a process for efiecting the intermolecular condensation of substantially HF-insoluble polynuclear aromatic hydrocarbons, preferably polynu-.

clear aromatic hydrocarbons containing only one naphthalenic structure such as naphathalene and alkylnaphthalenes, employing a catalyst consisting essentially of liquid, substantially anhydrous hydrogenfluoride. Another object of my inven-. tion is to convert HF-insoluble polynuclear aro matic. hydrocarbons by an intermolecular condensation reaction into HF-soluble polynuclear aromatic hydrocarbons which are separated from the reaction mixture as a solution in liquid hydrogen'fluoride. An additional object of my infrom the ensuing description of my invention read'in conjunction with the accompanying figures.

I have discovered that. HF-insoluble polynuclear aromatic hydrocarbons such as naphtha- The process lene and alkylnaphthalenes in the presence of liquid substantially anhydrous hydrogen fluoride catalyst The products of the condensation reaction may be removed from the reaction zone as a solution in liquid hydrogen fluoride when the latter is employed in quantity sufllcient to function not onlv as a catalyst but alsoas a'solvent for the reaction products. When the amount of hydrogen fluoride employed ;is insufficient to extract the desired amount of polynuclear aromatic hydrocarbon condensation productfrom the reaction mixture, at least a part of the reaction mixture may be extracted withadditional hydrogen fluoride either in the reaction zone or in a separate zone under conditions particularly favorable for the extraction operation.

I have made the surprising observation that mixtures of saturated hydrocarbons and 'I-IF-insoluble polycyclic aromatic hydrocarbons such as naphthalene or alkylnaphthalenes may be treated with a catalyst consisting essentially of liquid, substantially anhydrous hydrogen fluoride under certain operating conditions to effect intermolecular chemical condensation of saidaromatic hydrocarbons without simultaneousl effecting substantial cracking of said saturated hydrocarbons, although treatment of saturated hydrocarbons with liquid hydrogen fluoride under the same operating conditions in the absence of said aromatic hydrocarbons would result in appreciable or substantial cracking of said saturated hydrocarbons. In other words," the intermolecular chemical condensation of HF-insoluble polynuclear aromatic hydrocarbons ina mixture thereof with saturatedhydrocarbons, such as parafflns, can be made to proceed preferentially in the presence of a liquid substantially anhydrous hydrogen fluoride catalyst under reactionconditions Which would otherwise be suitable for-effecting substantial cracking of saturated hydrocarbons; By liquid, substantially anhydrous hydrogen fluoride I mean hydrogen fluoride which may contain up to about 10 weight per cent of Water, but which pref-. erably contains weight per cent or less, e. g. 1 or 2 weight per cent, of water.

' .When alkylnaphthalenes and the like containing relatively large alkyl groups, e. g. containing 5 or more carbon atoms, are subjected to the process of this invention, they tend to produce paraffin hydrocarbons having the same number of carbon atoms as the alkyl group, as Well as in termolecular condensation products.

, I have further made the surprising observation that mononuclear aromatic hydrocarbons, particularly a low boiling mononuclear aromatic hydrocarbon such as benzene may exert a sub- 4 stantial inhibiting eifect on the intermolecular chemical condensation reaction when present in the reaction zone in suflicient quantity whereas saturated hydrocarbons appear to exert substantially no inhibitory effect.

The intermolecular chemical condensation reactions herein under consideration may be catalyzed not only by liquid hydrogen fluoride but also by mixtures thereof with minor proportions of BF's, viz. about 1 to about 40 weight per cent of BFs based on the weight of hydrogen fluoride, preferably between about 1 and about 10 weight per cent BF3, although even less than 1 per cent of BFz may be used. Mixtures of HF and BFs appear to exert far greater catalytic activity than hydrogen fluoride alone in both intermolecular condensation and crackingreactions. Moreover, mixtures of HF and BFa exhibit remarkably different solvent powers from liquid hydrogen fluoride alone. Thus, mixtures of HF and BF3 exert far greater solvent capacity for all types of aromatic hydrocarbons than I-IF alone. Both monocyclic and polycyclic aromatic hydrocarbons are soluble to a substantial extent in mixtures of HF and BF3. Benzenoid-type dicyclic aromatic hydrocarbons are also soluble in I-IF-BFs mixtures. It is desired for the purposes of this invention to effect only the intermolecular condensation reaction with mixtures of HF and BFs; thereafter it is desirable to remove substantially all the BR;

from the reaction mixture and to effect extraction of said mixture with liquid substantially anhydrous hydrogen fluoride, which selectively dissolves the hydrocarbon produced by the intermolecular chemical condensation reaction.

Suitable HF-insoluble polycyclic aromatic hydrocarbons which may be subjected to intermolecular chemical condensation in accordance with this invention include naphthalene and alkylnaphthalenes, such as methylnaphthalenes, ethylnaphthalenes, propylnaphthalenes, n-butylnaphthalenes, sec-butylnaphthalenes, tert-butylnaphthalenes and the like. Preferred charging stocks are naphthalene, methyl-, ethyland tertbutylnaphthalenes. I may employ the pure polycyclic aromatic hydrocarbons or mixtures thereof as charging stocks or I may employ commercially available fractions containing these and similar polycyclic aromatic hydrocarbons, e. g., as found in certain kerosenes, furnace oils, hydroformer bottoms fractions, gas oils derived from thermal orcatalytic cracking operations, Diesel fuel fractions and the like.

In order to effect intermolecular condensation of said aromatic hydrocarbons it is important to avoid the presence of substantial amounts of mononuclear aromatic hydrocarbons, particularly a mononuclear aromatic hydrocarbon boiling below about 50 F. in the charging stock. Usually the presence of more than about 15 per cent by weight of a low boiling mononuclear aromatic hydrocarbon is undesirable since its presence in these or larger amounts may substantially retard or wholly prevent the propagation of the intermolecular condensation reaction of the polycyclic aromatic hydrocarbons. The low boiling mononuclear aromatic hydrocarbons are preferably re- When hydrogen :fluoride is employed as the sole catalyst, suitable temperatures for effecting the intermolecular chemical condensation. reaction fall between about 150F. andabout 450.F. However, the rate of the condensation reaction at temperatures below about 250 F. is too slow to be of practical significanceand I.have found it preferable to use temperaturesofat least about 250 F. Ordinarily I prefer to effect the intermolecular condensation reaction at temperatures between about 300 F. and about 450 F., for example at a temperature of about 330 F.

Sufiicient pressure is employed ineffecting the intermolecular condensation reaction to maintain at least a substantial proportion of the reactants and catalyst in the liquid phase. Whenhydrogen fluoride is employed as a sole catalyst suitable pressures usually fall between about-50 and about 1500p. s. i.

When hydrogen fluoride'is employed as the sole catalyst for the intermolecular condensation reaction, it may be used inamounts between about 0.5 and about or even a greater number of parts by weight (calculated as 100 per cent HF) per part by weight of chemically condensable polycyclic aromatic hydrocarbon in the charging stock. Ordinarily I prefer to employ between about 1 and about 15 parts by weight of liquid substantially anhydrous hydrogen fluoride per part of condensablearomatic hydrocarbon. The hydrogen fluoride employed for the purposes-of the present invention should contain at least about-90 per cent by weight of hydrogen fluoride. I prefer to employ commercial anhydrous hydrogenfiuoride which usually contains at least about 98per cent by weight of hydrogen fluoride.

The time of reaction will be correlated with the other reaction variables to secure the desired extent of intermolecular condensation. Ordinarily I may employ-reaction periods varying-between about 10'andabout 200 minutes, for ex-- ample about 60 minutes.

It'is desirable toefiect intimate contacting of the liquid hydrogen fluoride or other catalyst with the reactants. Conventionalequipment can be used to effect the necessary contacting in the course of the intermolecular condensation reaction, for example stirring and pumping equip ment suchas has been employed heretofore in effecting alkylation ofisoparaflins with-olefins in the presence of a liquid hydrogen fluoride-catalyst. The condensation reaction maybe carried out as. a batch, semi-continuous or continuous process. Bothchemical condensation and'extraction maybeeffected simultaneously-by continuously .counterflowing a hydrocarbon charging stock and liquid hydrogen fluoride catalyst througha vertical tower which may be packed, if desired, with HF-resistant materials to provide for intimate intermingling of the counterflowing streams. In another mode of operation the hydrocarbon charging stock may be caused to-flow upwards through a pool of liquid hydrogen-fluoride maintained in the reaction zone, when the temperature of operation is such'that the hydrogen fluoride phasezis the-more densephase.

Following the chemical condensation operation or in somednstances simultaneously therewith, steps are taken to effect the extraction ofpolynuclear aromatic hydrocarbonsproduced in'thev condensation reaction,.the extraction being effected with liquid-substantially anhydrous hydrogen fluoride. It may be preferred to eifect the condensationireaction andthe .solvent extraction operation under different operating, conditions.

6 Thus while it is ordinarilydesirable to effectin= termolecular condensation of polycyclic aromatic hydrocarbons with liquid hydrogen fluoride as the catalyst at temperatures above about 250- F. it is usually desirable to effect extraction ofthe resultant HF-soluble polynuclear aromatic hydrocarbons from the reaction mixture at temperatures below about 150 F., for example temperatures between about F. and 150 R, preferably between about F. and about 100 F. A suitable extraction operation can usually be effected at about room temperature. Furthermore ratio between about 0.1 and 1 whereas the ratio for the extraction operation can be higher, for example as high as 3 or even 5. In the condensa-.

tion reaction which iseflected at relatively high temperatures the possibility exists that the em- (ill ployment of a very high HFzoil ratio may result in the cracking of some of the saturated hydrocarbons, whereas at the relatively low temperature usually employed in the extraction operation, even very high HFzoil ratios will not induce substantial cracking of saturatedlhydrocarbons. The extraction operation will be effected under pressure sufficient to maintain the liquid phase in the extraction zone. Usually I may employ pressures between about 5 and about p. s. i. The extraction operation may be effected in conventional equipment such as is normally employed to effect selective solvent extraction of petroleum oils.

Referring to Figure 1, a suitable hydrocarbon charging stock comprising saturated hydrocarbons and HF-insoluble polycyclic aromatic hydrocarbons, which may be a kerosene fraction containing substantially no mononuclear aromatic hydrocarbon boiling below about 450 F., is passed from source It through line ll into heater l2 wherein it is heated to a suitable temperature, for example between about and about 450 F. From the heatenthe hydrocarbon charging stock passes into reactor [3 which is provided with agitating means such as paddle stirrer l4 and a temperature control jacket l5. Liquid, substantially anhydrous hydrogen fluoride is passed from storage tank is through valved line I I and heater l8 into reactor is.

Sufficient pressure is maintained in the reactor to hold the hydrocarbon reactants and the hydrogen fluoride catalyst for the most part in the liquid phase. is controlled by a. pressure control valve 19 in vent line 20. The pressure tends to increase during the course of the intermolecular condensation reaction since it proceeds withthe evolution of hydrogen. I

Upon completion of the desired reaction the reaction mixture is withdrawn from reactor l3 through line 2| and line 22 into settler 23. If desired, the settler may be operated under substantially the same conditions of temperature and pressure as those maintained in the reactor. Usually, however, it is desirable to operate the settler at a lower temperature and a correspondingly lower pressure. To this end it is usually desirable to withdraw at least a portion of the reaction mixture through valved line 24 and cooler 25 to adjust the temperature of the reaction mixture to a suitable value, usually below about 150 F.,.for: example,.about room tempera The back pressure on the reactor" 7 ture, before passing the mixture into the settler. The pressure in the settler is controlled by'pressure control valve 26 in vent line 21. In order to facilitate the settling and extraction which occur in settler 23 it may be desirable to addliquid hydrogen fluoride thereto through valved line 28' which is connected to valved line I! leading from HF storage 'tankle. In the settler a gas comprising a substantial portion of hydrogen is withdrawn through vent line 21.. An upper fluoride and extracted hydrocarbons such as quinonoid-type polynuclear aromatic hydrocarbons and I-IF-soluble polynuclear aromatic .hydrocarbons produced by the condensation reac tion is formed in settler 23. The extract phase is withdrawn through valved line 34, whence part or all thereof may be passed into line 3| for recycle to reactor l3. Usually it is undesirable to allow the hydrocarbon concentration of the hydrogen fluoride in the reactor to exceed about 40 weight per cent since an excessive amount of hydrocarbon in solution in the HF tends to reduce or impair its catalytic activity.

For this reason and for the further reason that it is usually desired to recover the polynuclear aromatic hydrocarbon formed in the intermolecular condensation reaction, at least a part of the extract phase in the reactor 23 is continuously or intermittently withdrawn through valved line 35 and heater 36 into tower 3? wherein HF is stripped from the extract phase. Temperatures between about 150 and about 500 F. and relatively low pressures such as 50 p. s. i. g. or even lower aremaintained in tower 37. a stripping gas may be introduced by line 38 into the lower portion of the tower to aid in the vaporization of the hydrogen fluoride. Suitable stripping gases compriselight paraffin hydrocarbons such as methane, ethane, propane, n-'

butane, isobutane, pentanes and the like. Hydrogen fluoride-soluble aromatic hydrocarbons are withdrawn from tower 31 through valved.

line 39. A vapor stream comprising hydrogen fluoride is withdrawn from tower 37 through valved line as whence it may be passed through condenser 4| and line 32 into HF storage tan:

3'! to aid in the vaporization of hydrogenfluoride it may be desirable to divert a portion of thegas stream from line 26 into valved line 43 and condenser 44 to liquefy its hydrogen fluoride content;'

from condenser 44 the gas-liquid mixture is passed into an accumulator drum 45, whence stripping gas is diverted through valved vent line 46 and liquid hydrogen fluoride is passed through valved line 4'1 which leads into line 42 passing into the hydrogen fluoride storage tank 16. The

If desired,

When a stripping gas is employed in tower operations it may be more desirable simply to dilute the extract phase with water or to dilute it with alkaline solutions whereupon the hydrocarbon materials contained in the extract phase will form a distinct phase which can be separated and utilized as desired. The disadvantage of this method-of operation, of course, is that the hydrogen fluoride is of no further use in the condensation reaction.

The oil fractions having relatively high con centrations of saturated hydrocarbons leaving the system through line 32 are adaptable to many uses depending upon their boiling ranges, viscosities and other properties. Thus, depend-' ing upon the charging stock passing to reactor 13, the oil fraction leaving through line 32 may be adapted for use as a burning oil, lubricating oil, high octane number Diesel fuel or as a charging stock for cracking processes. Thus when the relatively saturated hydrocarbon oil leaving the system through line 32 boils above the gasoline boiling range, e. g., in'the gas oil range, it may be subjected to cracking with liquid hydrogen fluoride as a catalyst or it may be cracked thermally or in the presence of solid cracking catalysts, for example alumina-silica or magnesia-silica type solid cracking catalysts under conventional conditions of temperature and pressure.

The hydrogen fluoride-soluble materials leaving the reaction system through line 39 comprise not only polynuclear aromatic hydrocarbons but also certain of the oleflnic, sulfur, nitrogen and oxygen compounds that may have been present in the charging stock. The polynuclear aromatic materials withdrawn through line 39 may be of value as chemical raw materials for such proc esses as oxidation, halogenation, nitration, sulfonation, amination, etc.; they may also be of value as insecticidal. materials, plasticizers for natural or synthetic rubbers, vinyl resins, etc.

Figure 2 illustrates an embodiment of my in vention wherein a minor proportion of BFs is employed as a promoter for hydrogen fluoride catalyst in the intermolecular condensation reaction but not in the subsequent extraction operation. A hydrocarbon charging stock comprising saturated hydrocarbons and HF-insoluble polycyclic aromatic hydrocarbons is passed from source [00 through valved line I0] and heater Hi2 into reactor I03 which is provided with a motor driven paddle stirrer or equivalent agitating means I04, a temperature control jacket I05 and a valved vent line I05 containing a pressure control valve 101. Hydrogen fluoride containing a minor proportion'of BFs, for example, about 0.5 to about 10 per cent of BF3 based on the weight of the hydrogen fluoride is passed from source' I08 through valved line I09 and heater H0 into the reactor. The reactor may be operated upon a charging stock such as cracked gas oil employing a catalyst:oil weight ratio between about 0.05 and about 1.0, e. g. about 0.5, at a temperature between about F. and about 250 F., e. g. about 9 the reaction mixture. A partor all of the HF may also be vaporized in the stripper. Suitable operating conditions for the stripper are a temperature between about 30 F. and about 150 F., and a pressure between about and about 40 p. s. i. g. Control of the temperature in the stripper may be facilitated by. passing all or part of the reaction mixture from line II I through valved line H4 into heater orcooler H5, whence it passes through line I I5 into line I I2 and thence into the stripper. To aid in the vaporization of BFs and, optionally, hydrogen fluoride in the stripper, a stripping gas may be introduced into the lower portion thereof through valved line I I1. Suitable stripping gases include light paraflin hydrocarbons such as methane, ethane, propane, etc.

When stripping gases are not employed or are introduced into the stripper in relatively small quantity,'the BF'a, which may also contain some HF, passing overhead through valved line II8 may be passed through compressor I I9 and cooler I into HF-BFs charging line I09 and passed into the reactor. Usually it is preferred to divert the gas stream from line I I8 through valved line I2 I, compressor I22 and cooler I23 into separating drum I24. In drum I24 hydrogen pro-- duced in the intermolecular condensation reaction eifected in reactor I03, BFs, and such stripping gases as..were introduced into stripper 'I I3 are removed through valved vent line I25; this gas stream may be treated to effect the recovery of BF3 by'conventional methods, for example by absorption in cold liquid hydrogen fluoride. Suit or settling tower I28. Usually it is desirable to pass at least a portion of the stripped reaction mixture through by-pass cooler I 2'IA before introducing itlinto tower I28. 7 a

If hydrogen fluoride has been added to reactor I03 in am'ountsufficient to serve not only as a catalyst but also as a solvent for the intermolecular condensation products, tower I28 may be utilized simply as a settling zone in which two liquid phases are formed, viz. an upper hydrocarbon phase containing a reduced content of condensable hydrocarbons and relatively enriched in saturated hydrocarbons and. a lower phase comprising a hydrogen fluoride solution of 'certain polynuclear aromatic hydrocarbons. I Ordinarily it is desirable to employ tower I28 both forfurther extraction of the reaction mixture with liquid hydrogenfluoride and as a settling zone. Tothis end liquid hydrogen fluoride from source I29 may be passed through valved line I30 and line I3l into the upper portion of tower I28. A liquid phase comprising hydrogen fluoride may be passed from drum I24 through valved line I32 through a heateror cooler I33 to join the hydrogen fluoride stream passing through line I 30.

A liquid stream relatively enriched in saturated hydrocarbons is withdrawn from the upper end of tower I28.:through'v'alved line I34. A liquid hydrogen .fluoride solutionof HFesolubLe and pressure may be maintained in the tower I23 when it ,isemployedfor extraction. 7 The I-IFzoil weight ratio employed in the extraction opera- ,tion will naturally depend on the specific constie tution of the hydrocarbons charged thereto but in general will fall between about 3.1 and about 'In tower I31 conditions are maintained suitable for. the vaporization of substantially all the hydrogen fluoride contained in the stream charged thereto. Suitable conditions are temperatures between about 150 F. and about 500 F. and pressures between about 0 and about 50 p. s. i. g. Hydrogen fluoride vapors are removed overhead through valved line I38 whence part or all thereof may be diverted through valved line I33 and condenser I00 for recycle through line IEI to join the hydrogen fluoride stream passing through line I3I into tower I28. The I-IF-soluble materials are removed from tower I31. through valved line I42. 1 I The specific examples presented in the following table will serve to illustrate the principles and some applications of the process of this invention, but it isrnot intended that they should serve unduly to limit the invention. The hydrogen fluoride employed in catalyzing the condensation reactions and to effect the extraction was commercial liquid, substantially anhydrous hydrogen fluoride. The reactions were efiected by'intimately agitating the liquid hydrogen fluoride with the charging stocks in a carbon steel pressure vessel having a capacity of 1575 00., provided with a stirrer which was operated at about 1725 R. PLLM. duringlzthe reaction period. Following stirring of the reactants for a period of time indicated in the table as contact time, stirring was. discontinued and liquid phases were allowed vto-separate in the pressure vessel by gravity settling. When the reaction temperature was above room temperature, the high temperature contacting was followed by ase'ttling period at room temperature; Y I Run -1 indicates that xylene, which maybe taken as typical of monocyclic aromatic hydrocarbons, is substantially insoluble in liquid vhydrogen fluoride at moderate temperatures. It was alsoobvious that no cracking had. occurred in this run.

Run 2 indicates that even at the high temper ature of 330 F. and the extended contacting period of 3 hours, liquid hydrogen fluoride dissolves substantially no toluene from its solution in n-heptane. Also notable is the fact that 20 volume per cent of toluene completely inhibited the cracking of n-heptane which would otherwise occur under these conditions; Run 2 also indicates very clearly that monocyclic aromatic hydrocarbons do not undergo intermolecular.

Run 3 shows that a dicyclic benzenoidhydrois employed simply as a set- V carbon, specifically amylnaphthalene, remains substantially undissolved in liquid hydrogen fluoride at room temperature. This run also indicates that more stringent operating conditions are necessary to effect condensation reactions 12 Run difiers from run 4 in that the n-heptane diluent of the latter was replaced by benzene. Run 5 demonstrates clearly that a relatively large amount of alow boiling aromatic hydro- 5 carbon not only inhibits cracking but also the with a dicyclic hydrocarbon. No cracking was intermolecular chemical condensation reaction observed to occur in this run. which otherwise proceeds preferentially with re- Run No 1 V 2 3 4 5 6 7 Feed:

Aromatic xyl ne---" toluene..- amyl-naphthalene. Z-Methylnaphthalene none.

Diluent 11- ept c n h ptane n-heptane. n-thepbenzeneoctane-.- cetane.

ane. Volume per cent diluent in feed 8O 80 8o 80 8O 84 HF. volume per cent on feed. 20' 20 2o 20 20 200 200. Reaction temp., F 70-80 330 1 70-80 330 330 330 329. Contract time, Hrs..- 0.33. 0.33. l 2 0,5 0,5, Refractive index (H1320)! Feed 1.4107"--- Rafiinale--- Feed solution 1.4332. 1.5226--- 1.4623.-- Raffinate solution 1.4234- 1.5228- 1.4496. Pure diluent 1.3890 1.3890... 1.5011... 1.4349... Weight per cent cracking products 0 n n 1.6.".-- 61.4. Aromatic removal, Weight per cent: 7

011110 0 0.0-- 22.2-. 0. 46.4"--- On actual Wei 0. 2.0 26.0....;' 4.0...." 57.0..."

1 Cooled to room temperature (7075 F.) to separate phases.

Run N0 8 9 10 11 12 13 14 V 15 16 Hydroformer Bottoms Fractions Furnace Oil Lube Oil 1 Feed: 7

Aromatic--. total 332495 11--- 495600 FL--- 495600 F! 600 F. Bottoms Diluent n-heptanen-heptane n-heptane n-heptane n-heptane 3 none.. none. none.. none. Volume per cent 80 80 80 80 diluent in feed. HF, golume per cent on 20 20 20 2o 20 20 20 52 52.

fee Reaction temp.. F -80 70-80 212 4 70-80 75.--" 330 330. Contact time, Hrs.- 0.33.- 0.33-- 48 0.33.. 1.0-.-- 1.1---- 1.25... 3.0.

Refractive index (m) Pure diluent- Specific Dispersion:

Fee

Raffinate" Weight per cent cracking products. Aromatic removal,

weight per cent:

I S. A. E. 20 grade oil from Mid-Continent crude oil.

9 Reaction mixture derived from run 10.

8 Contains 10% benzene.

4 Cooled to room temp. (7075 F.) to separate phases. 5 Calculated.

Runs 4, 5 and 6 were conducted upon 2-methylnaphthalene as the charging stock. In run 4, where n-heptane was the diluent, considerable chemical condensation occurred, as will be evident from the data concerning aromatic removal presented in the table. In run 4, the molecular weights of the aromatic hydrocarbons in the feed, raffinate and extract phases, respectively, were 142, 175 and 317. The molecular weight of the extracted aromatic hydrocarbon mixture indicates that it contains a considerable proportion of a dimer derived from the methylnaphthalene charging stock and also some higher molecular weight condensation products.

A comparison of run 4 with run 2, which was carried out under identical operating conditions, shows that intermolecular chemical condensation is characteristic of dicyclic aromatic hydrocarbons and not of monocyclic aromatic hydrocarbons.

spect to the cracking of paraffin hydrocarbons.

Run 6 like run 4 shows that intermolecular chemical condensation of an HF-insoluble polycyclic aromatic hydrocarbon can be readily effected in the presence of a saturated hydrocarbon having a relatively long chain which, as run 7 demonstrates, would undergo extensive cracking in the absence of polycyclic aromatic hydrocarbon. A comparison of run 6 with run 4 shows that a shorter contact time can be balanced or even overbalanced by the use of a larger amount of HF to effect the intermolecular condensation. Shortening the time in run 6 to /6 of that in run 4 but increasing the amount of hydrogen fluoride by 10-fold under otherwise similar operating conditions resulted in more extensive conversion and extraction in run 6 than were obtained in run 4.

The following is an analysis of the cracked products obtained from run 7. I

V agsaasoe It W111 be noted that although in run 7 extensive cracking of the cetane occurred, substantially no cracking occurred in run 6.

The charging stock in run No. 8 was hydro-- former bottoms containing hydrocarbons boiling from 332 F. to about 800 F. This run indicates that about 11 per cent of the total hydroformer bottoms was extracted by liquid hydrogen fluoride at about room temperature. Since the raffinate phase derived from run 8 has a considerably lower refractive index than the charging stock, this indicates that polycyclic aromatic hydrocarbons more highly condensed than naphe thalene are being removed as a solution in the liquid hydrogen fluoride. In order to study this phenomenon further the hydroformer bottoms was divided into two distillate fractions boiling,

I respectively, in the range 332 to 495 F. and 495 i to 600 F. and a residual fraction boiling from 600 F. to the end boiling point of the hydroformer bottoms. The n-heptane diluent of runs 9-12, inclusive, contained about 10 volume per cent of benzene.

Runs 9-and 10 indicate that fractions of the hydroformer bottoms comprising predominantly dicyclic aromatic hydrocarbons, specifically naphthalene and alkylnaphthalenes, do not dissolve appreciably in liquid hydrogen fluoride at moderate temperatures. The amount of aromatics extracted in run 12 from the highest boiling fraction of the hydroformer bottoms is in sharp contrast to the amounts of extract obtained in runs 9 and 10. The high degree of extraction obtained in run 12 is eXplainable on the basis that the fraction of hydroformer bottoms employed as the charging stock in that run contained substantial quantities of tricyclic quincnoid-type aromatic hydrocarbons such as an thracene and alkyl anthracenes.

However, an HF-insoluble fraction containing naphthalenes can be subjected to high temperature intermolecular condensation in the presence of HF, as in run 11, thereby producing HF- soluble polynuclear aromatic hydrocarbons. A comparison of run 11 with run 4 indicates that it is desirable to employ higher temperatures than 212 F., since at higher temperatures the intermolecular condensation reaction proceeds at a far greater rate. Run 11 also shows that by the process of this invention it is possible to separate I-lF-insoluble polycyclic aromatic hydrocarbons from HF-insoluble monocyclic aromatic hydrocarbons, providing the latter are not present in quantity suiflcient to prevent intermolecular chemical condensation of the former.

Run 13 shows that liquid hydrogen fluoride does not extract an appreciable proportion of hydrocarbons from a heavy oil such as furnace oil. The identical specific dispersion obtained on both feed and rafi'inate obtained in run 13 indicates that no extraction of aromatic hydrocarbons'has occurred. However, at elevated temperatures in the presence of HF, as in run 14,

there is an indication that an intermolecular condensation reaction of the dicyclic aromatic hydrocarbons occurs with resultant increase in the amount of hydrocarbons passing into solution in the liquid hydrogen fluoride. v The operation'of runl i -is of a type which would be useful 'inproducing a burner fuel of superior burning qualities or a Diesel fuel of improved 'cetane number. 1 I I Runs 15 and 16, relating to the treatment of a lubricating oilstock parallel runs 13 and 14, respectively. In run 15 the treatment of hydrogen fluoride at room temperature resulted in a limited degree of dearomatization, presumably by the extraction of quononoid-type polycyclic aromatic'hydrocarbons. At the higher temperature employed in run 16 a markedly-higher degree of aromatic hydrocarbon extraction was obtained because of the condensation of dicyclic aromatic hydrocarbons to HF-soluble polycyclic aromatic hydrocarbons.

The intermolecular chemical condensation of alkyl naphthalenes in the pre ence of a catalyst consisting essentially of liquid hydrogen fluor de is being cla med in my copending application 1 Ser al No. 135.166. filed December 2'7, 1949.

Having thus described my invention, what I claim is;

1. A process for effect ng the intermolecular conden ation of a substantiall HF-in oluble linear fused-ring polycyclic aromatic hydrocarbon, wh ch process compri es contactin said hydrocarbon in a reaction zone with a catalyst consistin essentially of liquid substantially anhydrous hydrogen fluoride and between about 1 and about do per cent by wei ht of BF3, ba ed on the weight of hydro en fluoride, at a temperature between a'nmif, gm F, and about 250 F. under pressure surficient to mainta n the liquid phase and for a period of time su ficient to e ect su stantial intermolecular condensation. withdrawing at least a portion of the reaction mixture from said reaction zone and removing at least a substantial por me. of the B therefrom by vap r zat n thereafter cooling the withdrawn reaction mixture and efiecting stratiflcation therein, whereby the withdrawn reaction mixture separates into a liquid pha e substantially insoluble in liquid hydrogen fluoride comprising unconverted linear fused-ring polycyclic aromatic hydrocarbon and a liquid pha e'comprising principally hydrogen fluoride and intermolecular chemical condensation products. se arating said liquid pha es and recovering ntermolecular condensation products from said liquid phase comprising principally HF and intermolecular chemi al condensation products.

2. A process for cite-stingtheintermolecularcondensation of a substantially HF-insoluble linear fused-ring polycyclic aromatic hydrocarbon, which process comprises contacting said hydrocarhop; in a reaction zone with a catalyst consisting essentially of liquid substantially anhydrous hybeing between about 10 and about 200 minutes,

withdrawing at least a portion of the reaction mixture from said reaction zone and removing at least a substantial portion of the BF3 therefrom by vaporization, thereafter cooling the withdrawn reaction mixture, adding additional liquid hydrogen fluoride and effecting stratification therein, whereby the withdrawn reaction mixture separates into a liquid phase substantially insoluble in liquid hydrogen fluoride comprising unconverted linear fused-ring polycyclic aromatic hydrocarbon and a liquid phase comprising principally hydrogen-fluoride and inter' molecular chemical condensation products, separating said liquid phases and recovering intermolecular condensation products from said liquid phase comprising principally HE and intermolecular chemical condensation products.

ARTHUR P. LIEN. 7

REFERENCES CITED The following references are of record in the file of this patent:

' OTHER REFERENCES Thomas, Anhydrous Aluminum Chloride In 10 Organic Chemistry, pub. Reinhold Pub. Corp.,

New York (1941), page 878 (1 page only) Scholl et al.,' Bericht 2202-9 (8 pages).

e, vol. 43 (1910), pages Feed read Refit/note Certificate of Correction Patent No. 2,525,809 October 17, 1950 ARTHUR P. LIEN It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Columns 11 and 12, in the table, first column, last two lines thereof, 7 for Raffinate Feed and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oifice. Signed and sealed this 2nd day of January, D. 1951.

[SEAL] THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

1. A PROCESS FOR EFFECTING THE INTERMOLECULAR CONDENSATION OF A SUBSTANTIALLY HF-INSOLUBLE LINEAR FUSED-RING POLYCYCLIC AROMATIC HYDROCARBON, WHICH PROCESS COMPRISES CONTACTING SAID HYDROCARBON IN A REACTION ZONE WITH A CATALYST CONSISTING ESSENTIALLY OF LIQUID SUBSTANTIALLY ANHYDROUS HYDROGEN FLUORIDE AND BETWEEN ABOUT 1 AND ABOUT 40 PER CENT BY WEIGHT OF BF3, BASED ON THE WEIGHT OF HYDROGEN FLUROIDE, AT A TEMPERATURE BETWEEN ABOUT 80*F. AND ABOUT 250*F. UNDER PRESSURE SURFICIENT TO MAINTAIN THE LIQUID PHASE AND FOR A PERIOD OF TIME SUFFICIENT TO EFFECT SUBSTANTIAL INTERMOLECULAR CONDENSATION, WITHDRAWING AT LEAST A PORTION OF THE REACTION MIXTURE FROM SAID REACTION ZONE AND REMOVING AT LEAST A SUBSTANTIAL PORTION OF THE BF3 THEREFROM BY VAPORIZATION, THEREAFTER COOLING THE WITHDRAWN REACTION MIXTURE AND EFFECTING STRATIFICATION THEREIN, WHEREBY THE WITHDRAWN REACTION MIXTURE SEPARATES INTO A LIQUID PHASE SUBSTANTIALLY INSOLUBLE IN LIQUID HYDROGEN FLUORIDE COMPRISING UNCONVERTED LINEAR FUSED-RING POLYCYCLIC AROMATIC HYDROCARBON AND A LIQUID PHASE COMPRISING PRINCIPALLY HYDROGEN FLUORIDE AND INTERMOLECULAR CHEMICAL CONDENSATION PRODUCTS, SEPARATING SAID LIQUID PHASES AND RECOVERING INTERMOLECULAR CONDENSATION PRODUCTS FROM SAID LIQUID PHASE COMPRISING PRINCIPALLY HF AND INTERMOLECULAR CHEMICAL CONDENSATION PRODUCTS. 